Hybrid Technology in Nuclear Medicine

In the X-ray that serves as the prototype of the initial investigative modality used basically cathode rays to create images of the human body parts on the fluorescent screens (Rappoport et al., 2004). This was effected by the emission of x-rays from the cathode ray tube. X-ray can be attenuated by different materials of different densities and can be transmitted through and can be captured by a photographic plate. Later, it was established that X-ray is electromagnetic in nature. These comprise of photons with specific wavelengths, frequency, and energy. The electromagnetic spectrum of X-ray can be divided into several bands. Those with long wavelengths were used in magnetic resonance imaging. The next significant wavelength is X-ray which is used in conventional radiography. Some ultra-short waves, which are high-energy gamma rays, are used in nuclear imaging (Valk et al., 2003).
Physical Principles of X-ray
If we consider the physical principles, X-rays are generated in an X-ray tube which comprises a vacuum tube with a cathode and an anode in an environment of high potential difference. When electricity is passed, the cathode current releases electrons at the cathode through thermal excitation. The voltage difference between the cathode and the anode then drives these electrons in an accelerated fashion which then hit the anode plate to release the energy, which in part is X-ray. It is important to be aware that in order to produce an image from the attenuated X-ray beam, these beams need to be captured and converted to an image. Recent advents of technologies have enabled digital capture of images. Traditionally, however, screen-film detectors and the image intensifiers are still in use. X-rays images are taken on photographic films (Ball and Moore, 1998). However, photographic films are very inefficient in capturing X-rays. The output image in a film is just 2% of the incident X-ray photons. This percentage of the photons indicates the absorption efficiency which is determined by the probability of an X-ray photon quantum absorbed by the detector.